Java 在 HashMap 中搜索给定键的值
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/3051486/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Search a value for a given key in a HashMap
提问by bhavna raghuvanshi
How do you search for a key in a HashMap? In this program, when the user enters a key the code should arrange to search the hashmap for the corresponding value and then print it.
你如何在 a 中搜索一个键HashMap？在这个程序中，当用户输入一个键时，代码应该安排在 hashmap 中搜索相应的值，然后打印出来。
Please tell me why it's not working.
请告诉我为什么它不起作用。
import java.util.HashMap;
import java.util.; import java.lang.;
public class Hashmapdemo
{
public static void main(String args[])
{
String value;
HashMap hashMap = new HashMap();
hashMap.put( new Integer(1),"January" );
hashMap.put( new Integer(2) ,"February" );
hashMap.put( new Integer(3) ,"March" );
hashMap.put( new Integer(4) ,"April" );
hashMap.put( new Integer(5) ,"May" );
hashMap.put( new Integer(6) ,"June" );
hashMap.put( new Integer(7) ,"July" );
hashMap.put( new Integer(8),"August" );
hashMap.put( new Integer(9) ,"September");
hashMap.put( new Integer(10),"October" );
hashMap.put( new Integer(11),"November" );
hashMap.put( new Integer(12),"December" );
Scanner scan = new Scanner(System.in);
System.out.println("Enter an integer :");
int x = scan.nextInt();
value = hashMap.get("x");
System.out.println("Value is:" + value);
}
}
采纳答案by Jon Skeet
回答by Tim Büthe
You wrote
你写了
HashMap hashMap = new HashMap();
...
int x = scan.nextInt();
value = hashMap.get("x");
must be:
必须是：
Map<Integer, String> hashMap = new HashMap<Integer, String>();
...
int x = scan.nextInt();
value = hashMap.get(x);
EDIT or without generics, like said in the comments:
编辑或不使用泛型，如评论中所述：
int x = scan.nextInt();
value = (String) hashMap.get(new Integer(x));
回答by Gagan Prajapati
//If you want the key to be integer then you will have to declare the hashmap //as below :
//如果您希望键为整数，则必须声明哈希映射 //如下：
HashMap<Integer, String> map = new HashMap<Integer, String>();
map.put(0, "x");
map.put(1, "y");
map.put(2, "z");
//input a integer value x
//输入一个整数值x
String value = map.get(x);
